Purpose: The purpose of this study is to understand which aspects that alterations and additional work affect the end result financially and what consequences it has. This study also wants to find out if there are similarities between different projects, regarding why and how alternations and additional work arise, as well as how this can be counteracted. This is done through interviews with various operators, literature studie and document analysis, finally the answers will be compiled and compared. Method: The method consists of data collection in the form of interview studie and document analysis based on different operators and projects with the aime of obtaining different perspectives. A literature studie was implemented based on course literature and relevant web pages in order to obtain basic information before the own investigation. Results: From the result it appears that the planning is the most important aspect to highlight as it lays the foundation for the entire project. It is possible to prevent alternations and additional work by having well executed construction documents, planning for alternations and additional work in case they arise and implementing basic investigations to have all the information about the project before the production starts. Conclusions: The conclusion of this studie is that it fulfilled its purpose when it became clear how alterations and additional work arise and what consequences it has financially. Alternations and additional work always arise regardless of the size of the project, but how the alternations and additional work arise varies. Alternations and additional work are almost always based on the start of the project when the entire project is planned and prepared for the production. It is therefore very important that the construction documents and other foundation work are correct in order to reduce the alternation and additional work as much as possible. In the projects that the study has included they contain low percentage of the alternations and additional work which affect the final results as it cannot give an overall picture of how the construction industry looks in terms of alternations and additional work.  Keywords:  Alternations and additional work, Economy, Turnkey contract, Apartment building, Constructions documents, Project planning, Production